I bought my '01 4.0L 5 spd auto 4x4 Ranger about two months ago. Shortly after I got it, I noticed an intermediate ping or rattle when it was cold but didn't worry about it. Now almost 3K miles later, it's driving me absolutely BUG*****!!!! It's to the point now where it doesn't care what the engine or ambient air temp is. It's a very specific ping. Very predictable. It only does it during mild, normal acceleration - specifically between 2500 -3000 RPM. Unfortunately, this is the RPM range the tranny keeps the motor in through most of the acceleration cycle. As soon as it shifts into 4th or 5th and the RPM's drop below 2500, it's like flipping a switch. Smooth and quiet for mile after mile at cruise as long as it stays under 2500. If I drop the hammer hard, it will run like hell and never make a peep, either. I've been running 87 octane in it, although I did just run a tank of 89 through to see if it made a difference. The only change was to the fill-up bill. Other than this issue, the truck runs great. No MIL lights or anything. I've combed through the posts here and read in many places about TSB 01-19-7 regarding engine carbon buildup, but this bulletin only covers trucks through 2000. Most of the complaints about pinging 4.0's seem to be on older model years. Should I go ahead and try the decarboning process or does this sound like something else? If it were the DPFE, I'd think the MIL would be throwing a fit and if it were carbon buildup, I wouldn't think it would immediately shut up as soon as it dropped under 2500 RPM when it shifts and it would ping while the hammer was down too. Not sure how to proceed. Any thoughts before I do something drastic like trade it back in for my old F-150?

 

It is not a "pinging" problem, it is the infamous "timing chain rattle". There is a TSB out on it (common problem), that requires the replacement of the primary timing cassette. See your dealer.

 

PW01 is correct. I have an 02 Edge 4.0L and it did the EXACT same thing since new. The sound would disappear once the engine warmed up to normal operating temp. I had the Timing Chain Tensioner fix-kit installed (under warranty) and it solved the problem. They will attempt to say that the noise is a design flaw and will not harm anything - just annoying, but I'm sceptical on that. Any "sound" is coming from metal to metal contact. Even though it is a lubricated contact, I don't like it.

If you don't have any warranty on this vehicle, the repair could be costly as they have to take apart the front of the engine. Check into it.

No need to waste money on anything higher than regular fuel, as it has nothing to do with that. As a matter of fact, my manual says NOT to use premium fuel.

 

My truck does the same thing...but putting in 93 octane fixes it. Mine is a 94, with a 4.0 in it. My mechanic thinks that it's preignition, and that the fuel is igniting too quickly. Higher octane fuel is harder to ignite. I wonder if I have the dreaded "timing chain syndrome" too.

Dan